A graduate certificate or diploma (the terms are used interchangeably in North America) in architecture denotes specialization in a sub-field or discipline of architecture gained through intensive graduate-level study. As such, it supplements an already established area of expertise (in architecture or not related to the field) and adds value to a previously earned Bachelor's or graduate degree. Delivered in various formats from residential to online, graduate certificates in architecture comprise 4 - 6 courses (typically 12 - 18 credit hours) taken in a prescribed sequence at the graduate level.
The concurrent graduate certificate or diploma in architecture allows students currently enrolled in a Master's or Doctoral degree program in the field to pursue an in-depth exploration of one aspect of their field. For example, a student working Master's in Architecture with a specialization in landscape architecture may take the Graduate Certificate in Urban Design to augment their expertise.
The stand-alone, direct-entry graduate certificate/diploma program in architecture provides an opportunity for graduate-level study of theory and research to students who are not interested in pursuing a full graduate degree. This could include professionals with a Bachelor's degree working in the field or anyone who does not have the time or interest in a traditional graduate program in architecture. Then too, some students who take the stand-alone certificate already have a graduate degree and use their certificate to augment a particular area of interest.
A selection, but not inclusive list, of graduate certificates/diplomas in architecture includes

Graduate Certificate of Architecture (Generalist)

Graduate Certificate in Architecture-Based Systems Integration

Graduate Certificate in Architectural Management

Graduate Certificate in Building Science

Graduate Certificate in Critical Studies in Architecture

Graduate Certificate in Community Planning

Graduate Certificate in Environment, Policy and Society

Graduate Certificate in Facility Management

Graduate Certificate in Historic Preservation

Graduate Certificate in History of Art and Architecture

Graduate Certificate in Landscape Architecture

Graduate Certificate in Property Repositioning and Turnaround Strategies

Graduate Certificate in Sustainable Architecture

Graduate Certificate in Urban Design and the Built Environment